| 摘要 |
PROBLEM TO BE SOLVED: To perform a projection exposure process always at a proper imaging performance by adjusting a focusing condition under the monitor of the intensity of leak light. SOLUTION: A part of exposure light is transmitted through a plane reflecting mirror 4 after the exposure light is incident thereon. The exposure light through the plane reflecting mirror 4, or leak light is detected with a photo detector 11, and the output signal thereof is fed to a control system 22. Then, the control system 22 refers to a data table 21 showing a relation between the quantity of the leak light and the fluctuation amount of the focal point position of a projection optical system. The control system 22 thereby finds the fluctuation amount of the focal point position of the projection optical system, depending on the output signal of the photo detector 11. Also, the control system 22 feeds a drive signal to a drive system 23, on the basis of the focal point position fluctuation amount so found and moves a stage 103 or even a plate 102 by the required amount in a Z-axis direction, depending on the drive signal. Thus, the focused condition of a mask 101 and the plate 102 relative to the projection optical system can be adjusted for the focal point position fluctuation of the projection optical system attributable to the exposure light absorption of a positive lens 3. |
